Burglar alarm switch

ABSTRACT

A burglar alarm switch is mounted on an object to be protected. It comprises a vibration producer for converting any tilting movement of the object into vibrations and a piezoelectric element associated therewith for transducing the vibrations into an electric warning voltage.

United States Patent 72] Inventor Tntsujl Shimada c/0 Daiko ElectronicsIndustrial Co. Ltd.,

No. 25-28, .1050, Higashino-cho, Hlgashiyodo-gawa-ku, Osaka, Japan [21Appl. No. 82,967

[22] Filed Oct. 22, 1970 [45] Patented Dec. 28, 1971 [32] PriorityNOV-27,1969

[54] BURGLAR ALARM SWITCH 10 Claims, 5 Drawing Figs.

52 U.S.Cl 310/84, 310/8.4, 310/8.5, 340/276, 340/280 [51] int. n H0lv7/00 [50] Field oiSearch 310/s,s.1,

[56] References Cited UNITED STATES PATENTS 3,056,951 10/1962 Tooni340/261 X 2,909,614 10/1959 Goyette... 340/261 X 2,282,3109 5/1942 Brown310/81 X 2,898,477 8/1959 Hoesterey 310/8.1 X

Primary Examiner-J. D. Miller Assistant Examiner-B. A. ReynoldsAttorney-Kurt Kelman ABSTRACT: A burglar alarm switch is mounted on anobject to be protected. It comprises a vibration producer for convertingany tilting movement of the object into vibrations and a piezoelectricelement associated therewith for transducing the vibrations into anelectric warning voltage.

PATENTEIJuaczsmn 333L271 sum 1 or 2 Fig.7

INVENTOR THTS LLJ'I SHIMHDH BY K K AGENT PATENTEB uttza 197i SHEET 2 BF2 INVENTOR T1973 I s HIMHDF) BURGLAR ALARM SWITCH The present inventionrelates to improvements in burglar alarms, and more particularly to aburglar alarm switch which is placed directly on a valuable object to beprotected, such as a work of art.

In accordance with this invention the burglar alarm switch comprises apiezoelectric element having output terminals, a concave race defining asupport surface, a ball having a contact surface and being arranged forfree-rolling movement on the concave race, either the support surface orthe ball contact surface being rough, and means fixedly mounting theconcave race on the piezoelectric element.

When the object whereon the switch is placed is tilted during anymovement thereof, an angular movement of the race is relation to theball will occur, causing the contact surface of the ball to move overthe support surface of the race so as to produce vibrations due to theroughness of one of the surfaces. The vibrations are transduced by thepiezoelectric element to produce an output voltage at the terminals.Means are connected to the terminals for producing an alarm signal inresponse to the output voltage.

According to one embodiment of the invention, the concave race is aroughened inner face of a hemisphere or a relatively fiat, dishedmember. A mating hemisphere or cover may be positioned thereover.

In another embodiment, the concave race is the inner face of acurvilinear loop and two intersecting loops.

Ready testing of the burglar alarm switch is possible if the ball offerromagnetic material, in which case a magnetic field may be applied tothe switch to move the ball and thus to ascertain that the device is instandby condition.

The means for fixedly mounting the concave race on the piezoelectricelement is a mount capable of transmitting the vibrations to thepiezoelectric element.

In accordance with a preferred feature of the present invention, thepiezoelectric element is fixedly mounted on a vibration absorber towhich a baseplate is attached and which, in turn, supports the element,preferably resiliently.

The objects and advantages of this invention, as well as the above andother features thereof, will become more apparent from the followingdetailed description of certain now preferred embodiments thereof, takenin conjunction with the accompanying drawing wherein FIG. 1 is anexploded view of a burglar alarm switch according to one embodimentillustrating the principle of the present invention,

FIG. 2 is a perspective view showing the switch of FIG. I in assembledcondition,

FIGS. 3 and 4 shown other embodiments of the present invention, and

FIG. 5 is a front view of a burglar alarm system in which the presentinvention is incorporated.

In the drawings like reference numerals designate like parts functioningin a like manner in all figures. In FIG. I, I and 2 are mating, hollowhemispheres of a nonmagnetic material with the inner faces thereof beingrough and enclosing a movable ball 3 freely rolling inside the sphere. Apress fitting 4 is provided with a mount 5 for fixedly supporting thevibrating hemispheres. The fitting has a base 7 fixed on the surface ofa piezoelectric element 6 which has output terminals 8. Thepiezoelectric element 6 is resiliently supported on a pair of rubberelements 9 provided on the surface of a baseplate 10. A vibrationabsorber ll of urethane foam or similar materials is glued to the bottomof the baseplate 10 with a suitable bonding agent, the above-mentionedparts being joined together, as shown in FIG. 2, to constitute a burglaralarm switch operating as follows:

The assembled burglar alarm switch is place on an object to be protectedwhich is put in a suitable case and remains stationary. If the object ismoved, conveyed or vibrated, it will be tilted so that the movable ballinside the hollow hemispheres will roll therein and thus come intocontact with the rough inner face of the hollow hemispheres to give riseto a slight impact vibration. This slight vibration will be transmittedto the piezoelectric element 6 through the press fitting 4, generating,electromotive force at the output terminals 8 of element 6. Theterminals are connected to a transmitter which is part of a burglaralarm system, together with a modulator, switch and a power source(refer to FIG. 5). Each time the movable ball 3 rolls and impinges onthe inner face of the hollow hemispheres, an electromagnetic wave willbe radiated from the transmitter. This alarm is received by a receiverlocated at a position distant from the object to put a burglar alarmlight, bell or the like in operation.

The impact between the movable ball and the rough faces, due to anyvariation of the angle of inclination to the piezoelectric element 6,will be transmitted regardless of the direction in which the objectmoves, thus ensuring operation under all conditions. It should, ofcourse, be understood that the same action and effect can be obtained byroughening the surface of the movable ball. The impact can be selectedby varying the radius of curvature and the roughness of the vibratinghemispheres and/or the movable ball and the mass of the movable ballaccording to the purpose aimed at.

When a fiat rough dish 21 is used in place of the vibrating hemisphere 2to enlarge the ratio of the radius of curvature of the vibratinghemisphere to the movable ball 3, as shown in FIG. 3, the rolling andmovement of the movable ball becomes more sensitive, resulting inproviding a burglar alarm switch capable of sensing the slightestvariation of an angle of inclination.

When the movable ball 3 is placed on two circular rails instead ofmounting in on the vibrating hemisphere 2, as shown in FIG. 4, thesensitivity of the switch to vibration becomes directional. In theembodiment depicted, the switch responds to impact, vibration anddisplacement in the direction parallel to the plane of the drawing buthardly senses impact, vibration and displacement in the directionperpendicular thereto.

It is possible by selecting the material and thickness of the vibrationabsorber 1] so as to absorb impact below a certain level to generate anoutput from the terminals 8 of the piezoelectric element 6 only when itis subjected to impact above a certain energy level, thereby preventingerroneous operations, for instance, when the burglar alarm switch ismounted on an article displayed at an exhibition and the switch issubjected to slight vibration caused by visitors walking nearby.

The piezoelectric element 6 used in this invention is so designed, inrespect of its electric characteristics, as to generate high voltagebetween the terminals thereof only when it is subjected to mechanicalimpact from outside Accordingly, economy in power consumption ispracticed as compared with prior detecting devices using a photoelectriccell, capacity change detection and the like, in which electric currentis kept flowing continuously to maintain the standby condition of thedevice.

Since the burglar alarm switch provided by this invention comprises avibrating concave race whereon a small movable ball is capable ofrolling in all directions, it is effective regardless of the position ordirection in which it is mounted on an object. In case it is subjectedto vibration or impact from outside, it will assume a standby conditionby itself immediately after the source of the vibration or impact ceasesto exist, thereby eliminating the necessity of removing this source andresetting the switch to the next standby position each time the switchfunctions, as in the case of prior burglar alarm switches.

Another advantage of the burglar alarm switch provided by this inventionis that, when the movable ball 3 is made of iron, nickel or otherferromagnetic substances, the movable ball 3 will move on the inner faceof the concave race under the influence ofa magnetic field as well asthe impact due to inclination caused by external force, so that anoutput is generated from the piezoelectric element 6. Thus, it ispossible to inspect and confirm whether the burglar alarm switchprovided in this invention is in the standby position for perfectfunctioning simply by applying a magnet 'to the race. This method onlyrequires the use of a magnet which will be moved toward the hemispheres2 of the burglar alarm switch of this invention.

The output terminals 8 of the burglar alarm switch of this invention canbe used only by incorporating in in a burglar alarm system comprising anoscillator, modulator, switch and power source, as shown in FIG. 5, butalso by connecting it to the detecting circuit of various types ofequipment with lead wires.

I claim:

1. A burglar alarm switch comprising 1. a piezoelectric element havingoutput terminal means;

2. a concave race defining a support surface;

3. a ball having a contact surface and being arranged for free rollingmovement on the concave race,

a. at least one of the surfaces being rough;

4. means fixedly mounting the concave race on the piezoelectric element,

b. angular movement of the race in relation to the ball causing thecontact surface of the ball to move over the support surface of the raceso as to produce vibrations, and said vibrations being transduced by thepiezoelectric element to produce an output voltage at the terminalmeans; and

5. means connected to the terminal means for producing an alarm signalin response to said output voltage. 2. The burglar alarm switch of claim1, wherein the concave race is a roughened inner face ofa hemisphere.

3. The burglar alarm switch ofclaim 2, further comprising a matinghemisphere positioned over the first-mentioned hemisphere.

4. The burglar alarm switch of claim I. wherein the concave race is aroughened inner face of a relatively flat. dished member.

5. The burglar alarm switch of claim I, wherein the concave race is theinner face of a curvilinear loop.

6. The burglar alarm switch of claim I, wherein the ball is offerromagnetic material.

7. The burglar alarm switch of claim I, wherein the means fixedlymounting the concave race on the piezoelectric element is a mountcapable of transmitting the vibrations to the piezoelectric element.

8. The burglar alarm switch of claim 1, further comprising a vibrationabsorber, and means for fixedly mounting the piezoelectric element onthe vibration absorber.

9. The burglar alarm switch of claim 8, wherein the lastnamed meanscomprises a baseplate attached to the vibration absorber and supportingthe piezoelectric element.

10. The burglar alarm switch of claim 9, wherein the piezoelectricelement is resiliently supported on the baseplate.

1. A burglar alarm switch comprising
 1. a piezoelectric element havingoutput terminal means;
 2. a concave race defining a support surface; 3.a ball having a contact surface and being arranged for free rollingmovement on the concave race, a. at least one of the surfaces beingrough;
 4. means fixedly mounting the concave race on the piezoelectricelement, b. angular movement of the race in relation to the ball causingthe contact surface of the ball to move over the support surface of therace so as to produce vibrations, and said vibrations being transducedby the piezoelectric element to produce an output voltage at theterminal means; and
 5. means connected to the terminal means forproducing an alarm signal in response to said output voltage.
 2. aconcave race defining a support surface;
 2. The burglar alarm switch ofclaim 1, wherein the concave race is a roughened inner face of ahemisphere.
 3. The burglar alarm switch of claim 2, further comprising amating hemisphere positioned over the first-mentioned hemisphere.
 3. aball having a contact surface and being arranged for free rollingmovement on the concave race, a. at least one of the surfaces beingrough;
 4. means fixedly mounting the concave race on the piezoelectricelement, b. angular movement of the race in relation to the ball causingthe contact surface of the ball to move over the support surface of therace so as to produce vibrations, and said vibrations being transducedby the piezoelectric element to produce an output voltage at theterminal means; and
 4. The burglar alarm switch of claim 1, wherein theconcave race is a roughened inner face of a relatively flat, dishedmember.
 5. The burglar alarm switch of claim 1, wherein the concave raceis the inner face of a curvilinear loop.
 5. means connected to theterminal means for producing an alarm signal in response to said outputvoltage.
 6. The burglar alarm switch of claim 1, wherein the ball is offerromagnetic material.
 7. The burglar alarm switch of claim 1, whereinthe means fixedly mounting the concave race on the piezoelectric elementis a mount capable of transmitting the vibrations to the piezoelectricelement.
 8. The burglar alarm switch of claim 1, further comprising avibration absorber, and means for fixedly mounting the piezoelectricelement on the vibration absorber.
 9. The burglar alarm switch of claim8, wherein the last-named means comprises a baseplate attached to thevibration absorber and supporting the piezoelectric element.
 10. Theburglar alarm switch of claim 9, wherein the piezoelectric element isresiliently supported on the baseplate.